We plan to study elastin degradation with the use of a recently developed radioimmunoassay for desmosine. This is feasible since desmosine crosslinks are unique to elastin and desmosines are not absorbed by the gastrointestinal tract. Accordingly, we plan to measure levels of desmosine excretion (as an index to elastin degradation) in subjects of various ages and in patients with a variety of diseases. We plan to study elastin synthesis in lung explant cultures and in cultures of fibroblasts derived from the lung. We have developed a specific radioimmunoassay which can detect extremely small quantities of soluble elastin. We plan to continue studies on the influence of cellular factors (including polymorphonuclear leukocytes) on the development and severity of experimentally induced elastase emphysema. We will study further details about the mechanism of collagen accumulation in the hamster following intratracheal instillation of bleomycin. We plan to use a sensitive solid-phase fibronectin assay for the detection of elastolytic activity from monocyte-macrophage like cells of several sources including human alveoli. We plan to explore the chemotactic activity of elastin peptides for monocytes and identify some of the factors which may influence the intensity of this activity. We plan to test these peptides for chemotactic activity against fibroblasts.